PROJECT SUMMARY Glucose-responsive delivery of insulin mimicking the function of pancreatic ?-cells to achieve meticulous control of blood glucose (BG) would revolutionize type 1 and advanced type 2 diabetes care. However, it is extremely challenging to demonstrate a system which would combine fast response, reversible activation, ease of administration and excellent biocompatibility. In this proposal, we aim to establish an innovative glucose-responsive insulin delivery system based on the interaction between the glucose derivative- modified insulin (Glu-insulin) and glucose transporters (GLUTs) on red blood cells (RBCs). This binding interaction is reversible in the setting of hyperglycemia, resulting in fast release of insulin and subsequent drop of blood glucose levels. We will exploit two conjugation formulations of Glu-insulin and glucose transporters (GIGTer): 1) polymeric nanoparticles (NPs; ~100 nm in diameter) coated with the RBC membrane (with GLUTs) and loaded with Glu-insulin; and 2) liposomal NPs integrated with exogenously expressed glucose transporters and Glu-insulin. We will further integrate these two glucose-responsive formulations into a painless microneedle (MN)-array based transcutaneous patch to obtain the ?smart insulin patch? (SIP). Glu-insulin encapsulated NPs will also be incorporated inside SIP for serving as insulin reservoir to ?recharge? GIGTers for up to 48 h regulation within a normoglycemic range. In vivo potency of smart insulin patch will be evaluated using the streptozotocin (STZ)-induced type 1 diabetic male C57B6 mice and Sprague Dawley rats. In Aim 1, we will validate and optimize the glucose-responsive capability of the GIGTers based on our preliminary study. In Aim 2, we will evaluate the effectiveness of SIPs integrated with GIGTers, determining the feasibility of utilizing the GIGTer as a new administration modality. In Aim 3, we will optimize the physicochemical properties of the GIGTer-integrated patches in type 1 diabetic mouse and rat (implanted with the Continuous Glucose Monitoring System, CGMS) models; we will substantiate the glucose-responsive capability as well as the biocompatibility of SIPs with GIGTers. The proposed goal, when successfully realized, will be a significant upgrade over the current insulin-dependent diabetes therapy options and have a profound impact to improve health and quality of life of diabetic patients.